From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id F30A1139083 for ; Wed, 22 Nov 2017 07:26:08 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id D2693E0E4C; Wed, 22 Nov 2017 07:26:03 +0000 (UTC) Received: from mail-wm0-x243.google.com (mail-wm0-x243.google.com [IPv6:2a00:1450:400c:c09::243]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 54144E0DEE for ; Wed, 22 Nov 2017 07:26:03 +0000 (UTC) Received: by mail-wm0-x243.google.com with SMTP id r68so8092074wmr.1 for ; Tue, 21 Nov 2017 23:26:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=1quayvJFkJ1xVBUXd4VK9CpkTEpt8NbZJfuj+rDD3Q4=; b=VnHDs2eXUXOgdxj/rSO/R6eDvypYTTvgJ+fITH9M2weK7f84SYH2Pv5pLikag3vdVa znbMTdG8PBLqCHyZYrIU/X8ERFxuwalsBMUL1hzDMFYJDRFMoMDfL0PEfGUV/Ti9P9Lc CZ4HkJbRPHUnmOXSr85JTYwRn9p3w2mOoeQvCqD+QVn5v7PTFiawa51rcSge++nSG/1x egPBZ5NO8XUJTuXbebMjezgDt8VxBqJip++nLP63HtrwWhA75Go2LHGzVcBrFMm+gkOB fh2rL1DlY5O9h7krxMsvdSr4w1mjRBpvyXkghknvjE2NLBgkNPzsBQunxJCe/1jmOD4B vUlQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=1quayvJFkJ1xVBUXd4VK9CpkTEpt8NbZJfuj+rDD3Q4=; b=L/rBTL3UbhHHuEHZUHKpFapU5AisukFUrLNM8RLYP1ZudO01c9ZiqE0NA//hO1I8LY ISKxGAfeCkNo9GaXYaehnmutED1d0y9cpitB9VKQf66Tc+n2iJTaIBXh1c2sqvmZ+B5/ 5DEvhdCayxuHKJf2ac6oj3gqLTtvNLFeR6IwSmJYu2W3bkwhDfK+pRBXYKMYisirr2Kd oDxE0sRZ/DDT6UvDBkRtNqXcUlhCf2McM+DR4y8jFn/6s9ZQg/hd4oU/WPVSeB66h66Z yjz4L580E/1lwDtTAVc0tzuzMczKGeBho2vYlCfGJI8GrOWpqQtP8eEhkZ7jW7zziSR8 18Zg== X-Gm-Message-State: AJaThX73qjLVLQqpIxIRx3LH0zLchSFrE0o0cWUb+rgc6q7RRtd420js P4matsUGo+Lg102E42e6UDTDAQ== X-Google-Smtp-Source: AGs4zMbc9jA3pIrM3bzrAB160xooMfUsT95Tg6datacNmHXXZUcUUhhGo7xmQLRJgDv2C5wKlbekYw== X-Received: by 10.28.206.142 with SMTP id e136mr3621063wmg.27.1511335561645; Tue, 21 Nov 2017 23:26:01 -0800 (PST) Received: from gentoo-tp ([2a02:908:1082:2f20:67b6:1d4a:8f6a:66d9]) by smtp.gmail.com with ESMTPSA id k30sm26600875wrf.63.2017.11.21.23.26.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 Nov 2017 23:26:00 -0800 (PST) Date: Wed, 22 Nov 2017 08:26:01 +0100 From: Jeremi Piotrowski To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] is multi-core really worth it? Message-ID: <20171122072601.GA18724@gentoo-tp> References: <6b5fbeca-453c-f103-5e4e-a8db83a6dabf@st.com> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6b5fbeca-453c-f103-5e4e-a8db83a6dabf@st.com> User-Agent: Mutt/1.7.2 (2016-11-26) X-Archives-Salt: 5cc2250b-00f7-4210-925a-9eb4a4ec104e X-Archives-Hash: 0753f6b5ef3c69c9efa7019ec3141d8d On Wed, Nov 22, 2017 at 07:52:54AM +0100, Raffaele Belardi wrote: > Hi, > > rebuilding system and world with gcc-7.2.0 on a 6-core AMD CPU I have the impression that > most of the ebuilds limit parallel builds to 1, 2 or 3 threads. I'm aware it is only an > impression, I did not spend the night monitoring the process, but nevertheless every time > I checked the load was very low. multi-core is definitely worth it. Any non-trivial package (wine,glibc,gcc,llvm,qt off the top of my head) will spend a long time building many files that can be built in parallel with multiple make jobs. That being said: if you do a world rebuild you will have lots of packages that spend ~40 seconds doing their autoconf run, only to build 2-3 sources files. On an 8-core machine at work, I get good results using parallel emerge jobs (emerge -jX). For your 6-core AMD CPU (assuming it actually has 12 threads) I'd start with 'emerge -j3' and MAKEOPTS='-j12 -l16'. That should get you a nice speedup, but may require a bit more ram.